Is a mid-2000’s boombox worthless? - I’d say probably yes or at least certainly a candidate for this thread:
https://www.badcaps.net/forum/showth...post+worthless
Long story long , my dad picked up a Sony CFD-E55 boombox over a decade ago from the trash room in a condo where we used to live.
(Note: picture below is of the boombox after the repair.)
He then put it in a box when we moved places and it sat in the garage for a few years. Eventually, I tested the boombox and found that it worked on batteries, but not on AC. Digging in revealed the internal line-connected transformer had an open primary winding and no thermal fuse (wires melted on a few layers, thus not able to repair it in any way, and I had to crack-open the plastic shell on the transformer, as seen on the pictures below.)
So I made a power plug for it to fit a spare 15V, 4 Amp laptop power adapter I had at the time. I even posted the repair here in the ghetto mod thread some 8 years ago.
Old picture of the repair: https://www.badcaps.net/forum/attach...3&d=1353991011
While that repair did work OK, I noticed that the amp IC would get quite hot, along with the linear regulator IC for the CD and Cassette Deck (hot enough to cause burning sensation, so probably 50-60°C.) I don’t know what voltage the original transformer output, but given that the output filter cap was rated at 16V, the DC voltage couldn’t have been higher and was probably in the 9-12V range. Thus, I suspect the 15V power adapter was probably giving a little higher voltage than originally, and hence why the regulators and amp IC ran hot. Nothing overheated with the 15V adapter, though, and the boombox did work OK like that. Moreover, it’s not like anyone used it much at the time, so for the most part, it sat idle in the garage. I actually did use it a few times when I found some old cassette tapes and was curious what was recorded on them. On that note, this Sony CFD-E55 actually has a really good, clean-sounding tape deck. Radio and CD also work great.
Jump “a few” years forward… with Covid-19 and everyone at home (myself included, as the company I worked for lay off its temp staff), my parents took on a lot of house projects. So my dad remembered this boombox again and asked me if I had fixed it so he could use it in the garage while working. I said, sure and set it up for him. But in the back of my head, I remembered the repair I did and wanted to re-visit it and improve on it - what better to do on a rainy day?
Starting with the power adapter I used (15V, 4 Amps)… let’s be honest: a boombox like this doesn’t really need such a large power adapter. Perhaps if the amp IC was one of those dual BTL jobbies, that current rating would have made sense. But this wasn’t the case here. The amplifier IC in the CFD-E55 is a Sanyo LA4601, which is a single-ended stereo amplifier chip. Its datasheet suggests that it can drive up to 2x 7 Watts (with ugly 10% THD ) into 3-Ohm speakers with Vcc of 15V. But it also states that if Vcc is 9V or less, the IC can be used without heatsink, which is how it was in this boombox (this hints the original transformer was probably rated at 12V or less.) All in all, though, the LA4601 amp IC is really nothing to write home about. The internal speakers in the CFD-E55 boombox are rated 3.2 Ohms and 3 Watts max. Doing the math… a 12V supply used in single-ended amp application means 6V max for the positive or negative peaks. Of course, the speakers would never see that, because of the biasing and internal voltage drops in the amplifier. So, assuming 2 voltage drops @ 0.7V for each 6V “side”, this leaves us with 4.4V max peak (and even that is probably somewhat inflated, but not unreasonable.) With the 3.2-Ohm built-in speakers, the max possible power from 12V should then be P = ((V_rms)^2) / R = [(4.4^2) / 2] / 3.2 = 3.025 Watts RMS. (In reality, the power output would probably be even lower, but this is a decent “best possible” approximation.) Thus, it looked like a 12V power adapter should be plenty to drive the speakers.
I wasn’t sure which of my 12V adapters to use (I have many), but I had quite a few like this one:
https://www.badcaps.net/forum/attach...1&d=1601752102
It is switching type, rated for 1.66 Amps at 12V, with a grounded plug. I load-tested it up to 1.6 Amps continuous, which it output with barely any voltage drop. What worried me more was the ground connection, as sometimes this can introduce line hum noise (especially if the boombox is to input or output audio to another grounded audio device.) I don’t plan on driving an amplifier with this boombox, though, and there are no auxiliary audio inputs, so the grounded adapter shouldn’t be a problem. Being switching type, it probably would interfere with AM reception, though.
Next step was to make a plug for the adapter. About 30 minutes later, and I had this:
A block of wood, a piece of nail, and a paper clip is all it took to make this, along with some drilling and cutting, of course. You can also see an ugly piece of aluminum I bent into an L-shape (more on that later below.)
Checking that the plug fit in the case as intended…
Painted and added some stickers (from recycled shipping labels ) for the expected voltage and current input, in case the adapter was ever lost (which shouldn’t matter, as I have two or three more of these spare):
To be continued… (10k char. limit always gets me )
part 1 of 2 posted
https://www.badcaps.net/forum/showth...post+worthless
Long story long , my dad picked up a Sony CFD-E55 boombox over a decade ago from the trash room in a condo where we used to live.
(Note: picture below is of the boombox after the repair.)
He then put it in a box when we moved places and it sat in the garage for a few years. Eventually, I tested the boombox and found that it worked on batteries, but not on AC. Digging in revealed the internal line-connected transformer had an open primary winding and no thermal fuse (wires melted on a few layers, thus not able to repair it in any way, and I had to crack-open the plastic shell on the transformer, as seen on the pictures below.)
So I made a power plug for it to fit a spare 15V, 4 Amp laptop power adapter I had at the time. I even posted the repair here in the ghetto mod thread some 8 years ago.
Old picture of the repair: https://www.badcaps.net/forum/attach...3&d=1353991011
While that repair did work OK, I noticed that the amp IC would get quite hot, along with the linear regulator IC for the CD and Cassette Deck (hot enough to cause burning sensation, so probably 50-60°C.) I don’t know what voltage the original transformer output, but given that the output filter cap was rated at 16V, the DC voltage couldn’t have been higher and was probably in the 9-12V range. Thus, I suspect the 15V power adapter was probably giving a little higher voltage than originally, and hence why the regulators and amp IC ran hot. Nothing overheated with the 15V adapter, though, and the boombox did work OK like that. Moreover, it’s not like anyone used it much at the time, so for the most part, it sat idle in the garage. I actually did use it a few times when I found some old cassette tapes and was curious what was recorded on them. On that note, this Sony CFD-E55 actually has a really good, clean-sounding tape deck. Radio and CD also work great.
Jump “a few” years forward… with Covid-19 and everyone at home (myself included, as the company I worked for lay off its temp staff), my parents took on a lot of house projects. So my dad remembered this boombox again and asked me if I had fixed it so he could use it in the garage while working. I said, sure and set it up for him. But in the back of my head, I remembered the repair I did and wanted to re-visit it and improve on it - what better to do on a rainy day?
Starting with the power adapter I used (15V, 4 Amps)… let’s be honest: a boombox like this doesn’t really need such a large power adapter. Perhaps if the amp IC was one of those dual BTL jobbies, that current rating would have made sense. But this wasn’t the case here. The amplifier IC in the CFD-E55 is a Sanyo LA4601, which is a single-ended stereo amplifier chip. Its datasheet suggests that it can drive up to 2x 7 Watts (with ugly 10% THD ) into 3-Ohm speakers with Vcc of 15V. But it also states that if Vcc is 9V or less, the IC can be used without heatsink, which is how it was in this boombox (this hints the original transformer was probably rated at 12V or less.) All in all, though, the LA4601 amp IC is really nothing to write home about. The internal speakers in the CFD-E55 boombox are rated 3.2 Ohms and 3 Watts max. Doing the math… a 12V supply used in single-ended amp application means 6V max for the positive or negative peaks. Of course, the speakers would never see that, because of the biasing and internal voltage drops in the amplifier. So, assuming 2 voltage drops @ 0.7V for each 6V “side”, this leaves us with 4.4V max peak (and even that is probably somewhat inflated, but not unreasonable.) With the 3.2-Ohm built-in speakers, the max possible power from 12V should then be P = ((V_rms)^2) / R = [(4.4^2) / 2] / 3.2 = 3.025 Watts RMS. (In reality, the power output would probably be even lower, but this is a decent “best possible” approximation.) Thus, it looked like a 12V power adapter should be plenty to drive the speakers.
I wasn’t sure which of my 12V adapters to use (I have many), but I had quite a few like this one:
https://www.badcaps.net/forum/attach...1&d=1601752102
It is switching type, rated for 1.66 Amps at 12V, with a grounded plug. I load-tested it up to 1.6 Amps continuous, which it output with barely any voltage drop. What worried me more was the ground connection, as sometimes this can introduce line hum noise (especially if the boombox is to input or output audio to another grounded audio device.) I don’t plan on driving an amplifier with this boombox, though, and there are no auxiliary audio inputs, so the grounded adapter shouldn’t be a problem. Being switching type, it probably would interfere with AM reception, though.
Next step was to make a plug for the adapter. About 30 minutes later, and I had this:
A block of wood, a piece of nail, and a paper clip is all it took to make this, along with some drilling and cutting, of course. You can also see an ugly piece of aluminum I bent into an L-shape (more on that later below.)
Checking that the plug fit in the case as intended…
Painted and added some stickers (from recycled shipping labels ) for the expected voltage and current input, in case the adapter was ever lost (which shouldn’t matter, as I have two or three more of these spare):
To be continued… (10k char. limit always gets me )
part 1 of 2 posted
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